I sort of assumed that the main difference between the American and
British dictionaries would be that the former would include 'color' and the
latter would only include 'colour'.

Unless I'm going insane, which I'm perfectly willing to accept is quite
likely, it seems that the British version actually accepts _both_
spellings, which isn't generally the desired behaviour.

$ echo "colour color Thrunge" | ispell -dbritish -l
Thrunge

Why are the British and American dictionaries included in the main ispell
package anyway? Should ispell be compiled to use 'default.hash' and a
symlink set up?